Control and Coordination

Control and Coordination

COMMUNICATION

• The nervous system is how you detect your environment, make decisions and then carry out movements

• Large and complex organisms detect changes in the external environment as well as changes within the body. They need to communicate this information to parts of the body where appropriate responses will be made.

  
  

COMMUNICATION

• We call changes that bring about responses stimuli. 

• The stimulus is detected by a receptor and an effector brings about a response. Since response often occurs in a different part of the body, efficient internal communication is also essential. 

• In mammals, internal communication involves both the nervous and endocrine (hormone-producing) systems. We will examine these next.

Central Nervous System

• Brain

• Spinal cord

Peripheral Nervous System

• To and from the central nervous system run nerves of the peripheral nervous system.

Multiple Choice

Responsible for integrating sensory information and responding accordingly.

• CNS

• PNS

• Both

Multiple Choice

Conveying motor commands to all voluntary striated muscles in the body

• CNS

• PNS

• Both

Multiple Choice

To connect the brain and the spinal cord to the limbs and organs.

• CNS

• PNS

• Both

Neurones – structure and function

• The nervous system is built from specialised nerve cells called neurones. 

• Each neurone has a cell body containing the nucleus and the bulk of the cytoplasm.

Neurones – structure and function

• From the cell body, extremely fine cytoplasmic processes run. 

• Many of these processes are very long indeed.

• They are specialised for the transmission of information in the form of impulses.

Neurones – structure and function

• Impulses are transmitted at speeds between 30 and 120 metres per second in mammals, so nervous co-ordination is extremely fast and responses are virtually immediate. 

• Another feature of the nerve impulse is that it travels to particular points in the body.

• Consequently, the effects of impulses are localised rather than diffuse.

Neurones – structure and function

• Another feature of the nerve impulse is that it travels to particular points in the body.

• Consequently, the effects of impulses are localised rather than diffuse.

Dendrites

• also dendrons, are branched protoplasmic extensions of a nerve cell that propagate the electrochemical stimulation received from other neural cells to the cell body, or soma, of the neuron from which the dendrites project.

Cell Body

• The cell body of a neuron contains the nucleus and lysosomes and is the site of synthesis and degradation of virtually all neuronal proteins and membranes.

Axon

• also called nerve fibre, portion of a nerve cell (neuron) that carries nerve impulses away from the cell body.

• A neuron typically has one axon that connects it with other neurons or with muscle or gland cells.

• Some axons may be quite long, reaching, for example, from the spinal cord down to a toe.

Myelin Sheath

• an insulating layer, or sheath that forms around nerves, including those in the brain and spinal cord.

• made up of protein and fatty substances

• allows electrical impulses to transmit quickly and efficiently along the nerve cells

Node of Ranvier

• periodic gap in the insulating sheath (myelin) on the axon of certain neurons that serves to facilitate the rapid conduction of nerve impulses

Schwann Cells

• a type of glial cells of the peripheral nervous system that help form the myelin sheath around the nerve fibers

• envelops and rotates around the axon forming myelin sheath

Glia Cells

• also called glial cells or neuroglia, are non-neuronal cells in the central nervous system (brain and spinal cord) and the peripheral nervous system that do not produce electrical impulses

• they maintain homeostasis, form myelin in the peripheral nervous system, and provide support and protection for neurons

Multiple Choice

A long single fibre that carries nerve impulses.

• Axon

• Dendrite

• Node of Ranvier

• Schwann Cell

Multiple Choice

A thick insulating layer around the axon.

• Dendrite

• Myelin Sheath

• Node of Ranvier

• Schwann Cell

Multiple Choice

A cell wrapped around the axon forming the myelin sheath.

• Node of Ranvier

• Dendrite

• Cell body

• Schwann Cell

Multiple Choice

Gap in the myelin sheath where axon is exposed

• Schwann Cell

• Cell Body

• Node of Ranvier

• Dendrite

Multiple Choice

Highly branched fibres that conduct impulses.

• Axons

• Dendrites

• Schwann cells

• Myelin sheath

 Sensory Neurons

• Receptors on senses detect stimuli

  Sensory neurons pass this information towards the Central Nervous System

• Have a single long dendron, which brings impulses towards the cell body, and a single axon which carries impulses away from the cell body

Relay Neurons

• also known as inter-neurones

• have numerous, short fibres

• each fibre is a thread-like extension of a nerve cell

• occur in the central nervous system

• they relay impulses to other neurones

• pass info from Sensory Neurons to Motor Neurons

 Motor Neurons

• have a cell body that lies within the brain or spinal cord

• pass information from CNS to effectors (muscles or glands)

How information is passed

• Signal travels ALONG neuron as an electrical Impulse

How information is passed

• As chemicals across the synapse BETWEEN neurons

Fill in the Blanks

Multiple Choice

How is information passed along a neuron

• as a chemical

• as electricity

• as a signal

• as an electrical impulse

Multiple Choice

Which type of neuron is found in the spinal cord?

• Motor

• Sensory

• Relay

• Effector

Multiple Choice

Which type of neuron carries information to muscle tissue?

• Sensory

• Relay

• Motor

• Effector

Multiple Choice

Which type of neuron passes information towards the CNS?

• Motor

• Sensory

• Effector

• Relay

Multiple Choice

How is information passed between neurons?

• As stimuli

• As electrical impulse

• As a chemical messenger

• They talk to each other

Multiple Select

Select ALL of the parts of the CNS?

• Brain

• Spine

• Spinal cord

• Sensory neurones

Recap - It's SIMple!

• Receptors detect stimuli

• Info is passed to CNS by Sensory Neurons

• The info is processed in the CNS by Inter Neurons

• A signal is then sent from the CNS to muscles/glands by Motor Neurons